# NNT Calculator

> Free number needed to treat (NNT) calculator. Enter events in two groups and get the NNT or NNH, the absolute risk reduction, a 95% confidence interval that handles intervals crossing zero, and a sentence for your manuscript.

Canonical: https://biostatkit.com/nnt

Enter the number of events in a treated and a control group and get the number needed to treat (or harm), the absolute risk reduction and a 95% confidence interval, plus a sentence for your manuscript.

## Methods wording

The absolute risk reduction and its 95% CI (Newcombe hybrid score method) were computed with BiostatKit [1]; the number needed to treat is its reciprocal, rounded up, with limits from inverting the CI of the absolute risk reduction [2].

Method: Newcombe-Wilson CI for the absolute risk reduction; NNT limits by inverting ARR limits (Altman).

## Frequently asked questions

### How do I interpret an NNT of 14?

On average, 14 people need to be treated for the follow-up period for one more person to avoid the outcome compared with control. Always state the period and the outcome.

### What does an NNT confidence interval running through infinity mean?

The CI of the absolute risk reduction includes 0, so the data are compatible with no effect, with benefit and with harm. Write it as NNTB to infinity to NNTH, as in the result panel.

### Can I get an NNT from an odds ratio or hazard ratio?

Not from this page. It needs the event counts in both groups. Converting an OR or HR needs an assumed baseline risk and gives a different, model-based number.

### Is my data stored or sent anywhere?

No. All calculations run in your browser tab. Nothing is uploaded, and the page works offline once loaded.

## Related calculators

- [Relative risk calculator](https://biostatkit.com/relative-risk)
- [Odds ratio calculator](https://biostatkit.com/odds-ratio)

Author: TS.BS. Vũ Duy Kiên (https://www.vuduykien.com)